Photographic processes



Unite 1 PHUTOGRAPHIC PROCESSES No Drawing. Application July 19, 1954 Serial No. 444,365

Qiairns. ((11. 9629) This invention relates to photography and, more particularly, to compositions and processes useful in the development of photosensitive silver halide elements.

It is one object of the present invention to provide novel compositions and processes employing such novel compositions for the development of silver halide emulsions.

A further object of the present invention is to provide novel chemical compounds capable of developing silver halide emulsions.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the compositions possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

It has noW been discovered that heterocyclic N-hydroxylamines and their salts are effective to develop exposed silver halide emulsions. These compounds contain at least one nitrogen in the ring, are monocyclic and may also contain oxygen in the ring. The preferred heterocyclic N-hydroxylamines are N-hydroxy morpholine, N- hydroxy piperidine and N-hydroxy pyrrolidine, and their salts.

The novel photographic developing agents of this invention may be prepared as follows:

Example 1 Molecular equivalents of pyrolidine and 6% hydrogen peroxide are allowed to stand together at room temperature for 20-24 hours. The solution is then extracted with ether, the ether extract dried, and the ether distilled off. The residue is vacuum fractionated to yield N-hydroxy pyrrolidine. The product boils at 74-76" C. at a pressure of 25 mm. and is soluble in alcohol, ether and alkali and moderately soluble in Water.

Example 2 N-hydroxy morpholine is prepared by allowing morpholine and hydrogen peroxide to react in a manner similar to that set forth in Example 1. The product is soluble in alcohol, ether and alkali, moderately soluble in water, and boils at 76-79 C. at a pressure of 3 mm.

Example 3 Nhydroxy piperidine is prepared by allowing piperidine and hydrogen peroxide to react in a manner similar to that described in Example 1. The product is soluble in alkali, alcohol and ether, moderately soluble in water, boils at 75-80 C. at a pressure of 18 mm. and melts at 3236 C.

The following is an illustration of a photographic developer composition useful in practicing this invention, and is not intended to limit the invention:

2 aten 2 Example 4 Water 7 cc Sodium sulfite grams 10 N-hydroxy morpholine do 0.6 Sodium hydroxide do 0.2

This developer composition fully develops a latent image present in a photosensitive silver halide emulsion, such as Kodak Verichrome, in about 5-8 minutes.

It will be apparent that the relative proportions of the novel developing agents and the other ingredients of the above developer composition may be varied to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the above developer composition by the substitution of preservatives or alkalies other than those specifically mentioned. It is also contemplated that, where desirable, the above developer composition may be modified by the inclusion of other common components of developer compositions, such as restrainers, accelerators, etc.

The novel developing agents herein disclosed are colorless, stain-free, stable and relatively nonvolatile (especially in the salt form) and give black silver deposits on development. They may be employed in the form of the free base or as acid salts thereof, such as the oxalate. Thus, the salt form may be employed where the developing agent is to be incorporated in, on or behind the emulsion, or Where one desires to prepare a dry leveloper composition, the solvent being added to the dry composition prior to use. Reference in this specification and in the claims to the developing agents in the form of the free base are therefore intended also to include instances where the developing agent is introduced as a salt. Thus, an alkaline solution will contain the free base even though it may have been initially added as a salt.

The heterocyclic N-hyclroxylamines of this invention are also useful as developing agents in diffusion-transfer reversal processes, both dye and silver, and are especially useful in such photographic processes wherein it is desired to eliminate or minimize the need for washing or stabilizing operations in liquid baths subsequent to the formation of the silver print. Examples of such processes are disclosed in U. S. Patent No. 2,647,056 to Edwin H. Land. The utility of the developers of this invention, however, is by no means limited to diffusiontransfer reversal processes, for they may be satisfactorily employed in conventional multistage and multibath photoglraphic processing procedures either in black-andwhile or color photography.

As noted above, the herein disclosed novel developing agents are useful in transfer processes of the type disclosed in the said patent to Edwin H. Land, and in other processes in which the problem of a residual stain cannot be readily met by washing operations. When used for transfer purposes, the novel developer compositions of this invention have incorporated therein as a further ingredient a silver halide solvent, such as sodium thiosulfate. If the composition is to be applied to the emulsion by being spread thereon in a thin layer, it may also include a film-forming thickening agent such, for example, as the high molecular weight polymer, sodium carboxymethyl cellulose.

Since certain changes may be made in the above compositions and processes, without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: i

1. A method of developing a silver halide emulsion which comprises treating an exposed silver halide emulsion containing a latent negative image with an aqueous solution containing an alkaline material and a. monocyclic, N-hydroxyl heterocyclic amine for a sufiicient time to develop the latent image to a silver image.

2. A method of developing a silver halide emulsion which comprises treating an exposed silver halide emulsion containing a latent image with an aqueous solution containing an alkaline material and a compound selected from the group consisting of N-hydroxy morpholine, N- hydroxy pyrrolidine and N-hydrox'y piperidine for a sufficient time to develop the latent image to a silver image.

3. A mehtod of developing a silver halide emulsion which comprises treating an exposed silver halide emulsion containing a latent image with an aqueous solution containing an alkaline material and N-hydroxy morpholine for a sufficient time to develop the latent image to a silver image.

4. A method of developing a silver halide emulsion which comprises treating an exposed silver halide emulsion containing a latent image with an aqueous solution containing an alkaline material and N-hydroxy pyrrolidine for a suflicient time to develop the latent image to a silver image.

5. A method of developing a silver halide emulsion which comprises treating an exposed silver halide emulsion containing a latent image with an aqueous solution containing an alkaline material and N -hydroXy piperidine for a sufficient time to develop the latent image to a silver image.

6. In a process of forming a silver transfer print by a diifusion-transfer reversal process wherein the latent image is developed by an aqueous composition comprising a silver halide developing agent, an alkali and a silver halide solvent, and unexposed silver halide is transferred to an image-receiving layer to form a positive silver image, the improvement which comprises effecting said development using a monocyclic, N-hydroxyl heterocyclic amine as the developing agent.

7. The process as defined in claim 6 wherein said N- hydroXyl heterocyclic amine is selected from the group consisting of N-hydroxy morpholine, N-hydroxy pyrorolidine and N-hydroxy piperidine.

8. The process as defined in claim 6 wherein said developing agent is N-hydroxy morpholine.

9. The process as defined in claim 6 wherein said developing agent is N-hydroxy pyrrolidine.

10. The process as defined in claim 6 wherein said developing agent is N-hydroxy piperidine.

References Cited in the file of this patent OTHER REFERENCES J. Am. Chem. Soc., vol. 72, May 1950, 311. 2280-2281. 

6. IN A PROCESS OF FORMING A SILVER TRANSFER PRINT BY A DIFFUSION-TRANSFER REVERSAL PROCESS WHEREIN THE LATENT IMAGE IS DEVELOPED BY AN AQUEOUS COMPOSITION COMPRISING A SILVER HALIDE DEVELOPING AGENT, AN ALKALI AND A SILVER HALIDE SOLVENT, AND UNEXPOSED SILVER HALIDE IS TRANSFERRED TO AN IMAGE-RECEIVING LAYER TO FORM A POSITIVE SILVER IMAGE, THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID DEVELOPMENT USING A MONOCYCLIC, N-HYDROXYL HETEROCYCLIC AMINE AS THE DEVELOPING AGENT. 